A. Field of the Invention
The invention relates to methods of treating cancers that express carcinoembryonic antigen (“CEA”), particularly medullary thyroid cancer (MTC), non-medullary thyroid cancers (non-MTC), colorectal cancers, hepatocellular carcinoma, gastric cancer, lung cancer, breast cancer and other cancers, in which CEA is expressed, by administering an immunological reagent comprising an antibody in combination with at least one other therapeutic agent, such as another antibody, a chemotherapeutic agent, a radioactive agent, an antisense oligonucleotide, an immunomodulator, an immunoconjugate or a combination thereof. The invention further relates to pharmaceutical compositions comprising the immunological reagent and at least one therapeutic agent in an unconjugated form. In particular, the invention relates to methods of treating cancers that express CEA by administering, prior to, with or after administering the therapeutic agent, a Class III anti-carcinoembryonic antigen (“anti-CEA”) monoclonal antibody (“MAb”), particularly a MAb, that has the binding affinity characteristics and specificities of corresponding murine Class III anti-CEA MAb, and more particularly humanized, chimeric or human MAbs, that possess more of the antigenic and effector properties of a human antibody. Particularly useful MAbs in the method of treatment are humanized MAbs in which the complementarity-determining regions (“CDRs”) of an anti-CEA murine MAb are grafted into the framework regions of a human antibody.
B. Background
CEA is an oncofetal antigen commonly expressed in a number of epithelial cancers, most commonly those arising in the colon but also in the breast, lung, pancreas, thyroid (medullary type) and ovary (Goldenberg et al., J. Natl. Cancer Inst. 57:11-22 (1976), Shively, et al., Crit. Rev. Oncol. Hematol. 2:355-399 (1985)). CEA was originally thought to be a tumor-specific antigen of colorectal cancer (Gold et al., J. Exper. Med., 122:467 (1965)). However, it was later found to be present in a diverse number of carcinomas, benign tumors, and diseased tissues, as well as in normal human colon (Shively et al., Crit. Rev. Oncol. Hematol., 2:355 (1985); von Kleist et al., Proc. Natl. Acad. Sci. USA., 69:2492 (1972)). CEA has been shown to mediate cell-cell adhesion through homotypic and heterotypic interactions, which in turn have implicated a role for CEA in various aspects of tumorigenesis.
Medullary thyroid cancer (MTC) confined to the thyroid gland is potentially curable by total thyroidectomy and central lymph node dissection. However, disease recurs in approximately 50% of these patients. In addition, the prognosis of patients with unresectable disease or distant metastases is poor, less than 30% survive 10 years (Rossi et al., Amer. J. Surgery, 139:554 (1980); Samaan et al., J. Clin. Endocrinol. Metab., 67:801 (1988); Schroder et al., Cancer, 61:806 (1988). These patients are left with few therapeutic choices (Principles and Practice of Oncology, DeVita, Hellman and Rosenberg (eds.), New York: JB Lippincott Co. 1333-1435 (1989); Cancer et al., Current Problems Surgery, 22:1 (1985)). Chemotherapy has been of little value and radiation therapy may only be used to control local disease (Cancer et al.; Tubiana et al., Cancer, 55:2062 (1985)). Thus, new therapeutic modalities are needed to control this disease.
A useful approach to cancer therapy and diagnosis involves the use of targeting antibodies to deliver therapeutic and diagnostic agents directly to the site of a malignancy. Over the past decade, a wide variety of tumor-specific antibodies and antibody fragments have been developed, as have methods to conjugate the antibodies to therapeutic agents, such as drugs, toxins, radionuclides, immunomodulators, such as cytokines or other agents, and to administer the conjugates to patients that target the tumor. However, patients treated with drugs or radionuclides complexed with murine monoclonal antibodies (which have been the most commonly used targeting antibodies for humans) develop circulating human anti-mouse antibodies (HAMAs) and sometimes a generalized immediate type-III hypersensitivity reaction to the antibody moiety of the conjugate. But these problems have been minimized by making these murine antibodies less immunogenic by a number of different methods, which include making humanized, chimeric or human antibodies, by chemically modifying the targeting antibody, such as by conjugating to polyethylene glycol to the targeting antibody (PEGylation), or by characterizing the situs of antigenicity in an antibody and then removing it; e.g., Fab′, F(ab)2 and other antibody fragments have been used in place of whole IgG. In addition, attempts have been made to reduce the adverse effects of HAMA by plasmaphoretically removing HAMA from blood. Immunosuppressive techniques also have been used to ameliorate the adverse effect of the foreign antibody sufficiently to permit multiple treatments with the targeting agent.
Regardless of these treatment advances, there still exists a need to provide more effective methods of treating CEA-expressing cancers. The present invention provides an effective therapy utilizing anti-CEA antibodies, such as a Class III anti-CEA MAb, the murine MN-14 MAb as defined in U.S. Pat. No. 5,874,540 and Hansen et al., Cancer, 71:3478 (1993), and a Class III anti-CEA MAb, the chimeric and humanized MN-14 MAbs as also defined in U.S. Pat. No. 5,874,540, and the NP-4 as defined in U.S. Pat. No. 4,818,709 by Primus et al., for example, all incorporated herein in their entirety by reference. Preferably, the Class III anti-CEA MAb is humanized, and used in combination with a therapeutic agent, particularly a chemotherapeutic agent, to yield an effective therapeutic treatment for CEA expressing cancers with minimal toxicity. Additionally, other anti-CEA antibodies, such Class II MAbs, for example, MN-6 (see Hansen et al., above, and NP-3 (se U.S. Pat. No. 4,818,709), and Class I MAbs, such MN-3 and MN-15 (see also Hansen et al., above) provide effective methods of treating CEA expressing cancers. Further, the separate administration of these two components provides enhanced results and the versatility and the flexibility to tailor individual treatment methods.